1. Field
The following description relates to a selective sonication-assisted deposition method of inorganic particles and chabazite (CHA) zeolite membranes grown from seeded layers on substrates using the method and plate-like all-silica CHA (Si-CHA) zeolite particles used for seed layer formation and manufacturing method of the same, and more particularly, to a selective sonication-assisted deposition method of inorganic particles and CHA zeolite membranes grown from seeded layers on substrates using the method and plate-like Si-CHA zeolite particles used for seed layer formation and manufacturing method of the same, in which thin particles can be selectively deposited on a substrate or on a support, and even a physical interaction alone allows for obtaining high surface coverage to form a uniform layer, which is critical in reproducible production of membranes of inorganic materials, such as zeolite, by secondary growth.
2. Description of Related Art
Zeolites are aluminosilicate crystallines employed in a wide range of applications including catalysis, separation, water softening, and adsorption. The rigid molecular-sized pore structures within zeolites are desirable for use in separations because they allow for the distinguishing and separating of gas molecules based on the difference in their sizes and/or shapes. Thus, this intrinsic molecular sieving property holds promise in selectively isolating CO2 from mixtures, for example, the mixture comprising CO2/N2/H2O that result from the post-combustion processes and the mixture containing CO2/CH4/H2O in the natural gas stream.
Among zeolites, the pore sizes of eight membered rings (MRs) lie in the range suitable for CO2 separation, as they are a little larger than CO2 and smaller than or similar to the sizes of N2 or CH4. Specifically, the molecular sizes (kinetic diameters) of CO2, N2, and CH4 are 0.33 nm, 0.364 nm, and 0.38 nm, respectively, whereas the maximum free dimension of 8 MRs is about 0.43 nm. Multiple 8 MR zeolite membranes have been fabricated in an attempt to capture CO2 from mixtures. Specifically, 8 MR zeolite and zeolite-like membranes such as DDR, SSZ-13 (CHA type) and SAPO-34 (CHA type) membranes have exhibited high performance for CO2 separation. Of these two types, the pore apertures of all-silica CHA (for convenience, referred to as Si-CHA from now on) zeolites are about 0.370 nm×0.417 nm, which enables discrimination of CO2 and N2 by their size difference. Although the separation of CO2 from N2 can be achieved by size exclusion using 8 MR pore apertures, the separation of CO2 from H2O is more challenging due to the smaller molecular size of H2O (0.265 nm). In order to minimize H2O flux through CHA zeolite, hydrophilic properties, presumably due to Al constituents in CHA frameworks should be minimized, requiring all-silica constituents.
Despite the high potential for CO2 separations even in the presence of H2O, to the best of inventors' knowledge, Si-CHA zeolite membranes have not yet been reported. In particular, the uniform formation of a layer (often called a “seed layer”) in the secondary growth method is important for attaining continuous CHA films or membranes via subsequent hydrothermal growth. However, it is challenging to synthesize submicrometer-sized and monodispersed Si-CHA zeolite particles, thus hindering the formation of uniform layers and accordingly, continuous films or membranes by secondary growth. The difficulty of the synthesis can be attributed to the inhomogeneous environment in a solid-like precursor in fluoride media, which was known as an effective way to synthesize Si-CHA zeolite up to now (M. J. Diaz-Cabanas, P. A. Barrett, M. A. Camblor, Chem. Commun. 1998, 1881-1882). In addition, a preferential out-of-plane orientation in the seed layer is critical in manufacturing films or membranes with the same orientation, and often improving their separation performance by providing desired pore channels along the film or membrane thickness (Z. Lai, G. Bonilla, I. Diaz, J. G. Nery, K. Sujaoti, M. A. Amat, E. Kokkoli, O. Terasaki, R. W. Thompson, M. Tsapatsis, D. G. Vlachos, Science 2003, 300, 456-460., J. Choi, S. Ghosh, Z. P. Lai, M. Tsapatsis, Angew. Chem., Int. Ed. 2006, 45, 1154-1158).